Hussein Rasool Abid

Adsorption of CH4 and CO2 on Zr-metal organic frameworks.

Zirconium-metal organic frameworks (Zr-MOFs) were synthesized with or without ammonium hydroxide as an additive in the synthesis process. It was found that addition of ammonium hydroxide would change the textural structure of Zr-MOF. The BET surface area, pore volume, and crystal size of Zr-MOF were reduced after addition of ammonium hydroxide. However, the crystalline structure and thermal stability were maintained and no functional groups were formed. Adsorption tests showed that Zr-MOF presented much higher CO(2) adsorption than CH(4). Zr-MOF exhibited CO(2) and CH(4) adsorption of 8.1 and 3.6 mmol/g, respectively, at 273 K, 988 kPa. The addition of ammonium hydroxide resulted in the Zr-MOF with a slight lower adsorption of CO(2) and CH(4), however, the selectivity of CO(2)/CH(4) is significantly enhanced.

Excellent performance of copper based metal organic framework in adsorptive removal of toxic sulfonamide antibiotics from wastewater

The increasing concerns on toxicity of sulfonamide antibiotics in water require a prompt action to establish efficient wastewater treatment processes for their removal. In this study, adsorptive removal of a model sulfonamide antibiotic, sulfachloropyridazine (SCP), from wastewater is presented for the first time using a metal organic framework (MOF). A high surface area and thermally stable MOF, HKUST-1, was synthesized by a facile method. Batch adsorption studies were systematically carried out using HKUST-1. The high surface area and unsaturated metal sites resulted in a significant adsorption capacity with faster kinetics. Most of the SCP was removed in 15min and the kinetic data were best fitted with the pseudo second order model. Moreover, isothermal data were best fitted with the Langmuir model. The thermodynamic results showed that the adsorption is a spontaneous and endothermic process. The adsorption capacity of HKUST-1 is 384mg/g at 298K which is the highest compared to most of the materials for the antibiotics. The high adsorption capacity is attributed mainly to π-π stacking, hydrogen bonding and electrostatic interactions.

Amino-functionalized Zr-MOF nanoparticles for adsorption of CO2 and CH4

Amino-functionalized Zr-MOF (amino-Zr-MOF) was synthesized using 2-aminoterephthalic acid as an organic linker. The physicochemical properties of the material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and N2 adsorption to understand its crystalline structure, morphology, thermal stability, and porous structure. CO2 adsorption isotherms on amino-Zr-MOF were obtained at 1 atm and at different temperatures. In addition, CO2 and CH4 adsorption at high pressure (up to 10 atm) was also measured. CO2 adsorption capacity on amino-Zr-MOF was 9 mmol/g at 988 kPa, 0°C, while CH4 adsorption capacity was 3.7 mmol/g at 900 kPa, 0°C. The heat of CO2 adsorption on amino-Zr-MOF was estimated to be 29.4 kJ/mol. Continuous column tests of CO2 adsorption were performed at different concentrations of CO2 in nitrogen at 20 mL/min and 0.7 g adsorbent and total adsorbed amounts of CO2 within the column during the breakthrough time were calculated to be 4.55, 5.26 and 4.37 mmol/g at 10%, 15% and 20%CO2, respectively.

Effects of ammonium hydroxide on the structure and gas adsorption of nanosized Zr-MOFs (UiO-66)

Several zirconium-based metal-organic frameworks (Zr-MOFs) have been synthesized using ammonium hydroxide as an additive in the synthesis process. Their physicochemical properties have been characterized by N(2) adsorption/desorption, XRD, SEM, FTIR, and TGA, and their application in CO(2) adsorption was evaluated. It was found that addition of ammonium hydroxide produced some effects on the structure and adsorption behavior of Zr-MOFs. The pore size and pore volume of Zr-MOFs were enhanced with the additive, however, specific surface area of Zr-MOFs was reduced. Using an ammonium hydroxide additive, the crystal size of Zr-MOF was reduced with increasing amount of the additive. All the samples presented strong thermal stability. Adsorption tests showed that capacity of CO(2) adsorption on the Zr-MOFs under standard conditions was reduced due to decreased micropore fractions. However, modified Zr-MOFs had significantly lower adsorption heat. The adsorption capacity of carbon dioxide was increased at high pressure, reaching 8.63 mmol g(-1) at 987 kPa for Zr-MOF-NH(4)-2.

Adsorptive removal of antibiotic sulfonamide by UiO-66 and ZIF-67 for wastewater treatment

Adsorptive removal of a toxic sulfonamide antibiotic, sulfachloropyradazine (SCP), from aqueous solution was studied on several metal organic frameworks, UiO-66 and ZIF-67, for the first time. UiO-66 exhibited a much higher adsorption capacity than ZIF-67, fast kinetics, and easy regeneration for reuse, demonstrating as a promising adsorbent in wastewater treatment processes. The batch adsorption shows an adsorption capacity of SCP at 417mg/g on UiO-66. The kinetic adsorption of SCP on UiO-66 reached equilibrium just in 10min and the kinetics fits accurately with a pseudo 2nd order model. A plausible mechanism was proposed based on pH effect, pKa value of the adsorbate and Zeta potential of UiO-66. The high adsorption is mainly contributed to hydrophobicity and π-π interactions along with electrostatic interactions. Thermodynamic studies show the spontaneous adsorption and exothermic process. The easy regeneration and high adsorption capacity confirms structural stability of the robust UiO-66 in wastewater treatment processes, making it suitable for a large scale application.

One-pot synthesis of binary metal organic frameworks (HKUST-1 and UiO-66) for enhanced adsorptive removal of water contaminants

In this study, binary metal organic frameworks (MOFs) with HKUST-1 and UiO-66 have been synthesized in a one-pot process. The synthesized MOFs were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption, and thermogravimetric analysis (TGA). The meso-porosity and thermal stability of the binary MOFs were higher than those of single HKUST-1 or UiO-66. The synthesized MOF hybrids were then tested for adsorptive removal of methylene blue (MB) from wastewater in terms of kinetic and isothermal adsorption as compared to a commercially available activated carbon (AC). All the synthesized MOFs showed significant removal of MB under a wide range of pH. The adsorption capacities of HKUST-1 are higher than UiO-66 and commercial AC while the binary MOFs presented an even higher adsorption capacity than single MOFs. This is the first time that binary HKUST-1 and UiO-66 MOFs have been successfully synthesized and demonstrated enhanced adsorptive removal of contaminants.

Removal of monoethylene glycol from wastewater by using Zr-metal organic frameworks

Mono-ethylene glycol (MEG), used in the oil and gas industries as a gas hydrate inhibitor, is a hazardous chemical present in wastewater from those processes. Metal-organic frameworks (MOFs) (modified UiO-66∗ and UiO-66-2OH) were used for the effective removal of MEG waste from effluents of distillation columns (MEG recovery units). Batch contact adsorption method was used to study the adsorption behavior toward these types of MOFs. Adsorption experiments showed that these MOFs had very high affinity toward MEG. Significant adsorption capacity was demonstrated on UiO-66-2OH and modified UiO-66 at 1000 mg·g-1 and 800 mg·g-1 respectively. The adsorption kinetics were fitted to a pseudo first-order model. UiO-66-2OH showed a higher adsorption capacity due to the presence of hydroxyl groups in its structure. A Langmuir model gave the best fitting for isotherm of experimental data at pH = 7.